Syria's new authorities under interim President Ahmed al-Sharaa have sought to disband armed groups
The Syrian Observatory for Human Rights war monitor has reported that 745 Alawite civilians were killed in Latakia and Tartus provinces.
Syrian authorities said the violence began when remnants loyal to Assad launched a deadly and well-planned attack on their forces on Thursday.
There were no immediate claim of responsibility for the attack.
Sharaa was appointed Wednesday to lead Syria for an unspecified transitional period
No group has claimed the four activists' abduction and they have not been heard from since.
Ankara-backed rebels played a key role in supporting Sharaa's Islamist group Hayat Tahrir al-Sham (HTS), which headed a rebel alliance that seized Damascus on December 8, toppling longtime ruler Bashar al-Assad.
The seismic change in Syria is expected to yield deeper Turkish sway just as a change of US administration is raising questions over how long Washington will keep backing the country's Kurdish-led forces.
Assad fled Syria following a lightning offensive spearheaded by the Islamist Hayat Tahrir al-Sham (HTS), more than 13 years after his crackdown on democracy protests precipitated one of the deadliest wars of the century.
Turkish air force jets carry out fresh strikes against Islamic State (IS) positions in Syria and also hit Kurdish militants in northern Iraq.
Turkish planes have for the first time carried out air strikes against Islamic State (IS) group targets in Syria.
A nurse who said he was forced to work with the so-called Islamic State is thought to be returning to Australia.
A US air strike reportedly kills Muhsin al-Fadhli, the Kuwaiti leader of the Khorasan Group, a shadowy al-Qaeda offshoot operating in Syria.
Turkish PM Ahmet Davutoglu promises to boost security along the country's border with Syria, after 30 people were killed by a bomb in the town of Suruc.
The Islamic State group fired chemical weapons against Kurdish forces in Syria and Iraq last month, Kurdish fighters and weapons experts have said reports The Economic Times.
A man - who joined Islamic State in Syria with 11 other family members of his family - is being held against his will after being "tricked" into going, his son tells British TV channel.
The US-led coalition fighting the Islamic State group is "intensifying" its campaign in northern Syria, President Barack Obama says.
British bank HSBC fires six staff after they filmed a mock Islamic State-style execution video during a team-building day out and posted footage online.
A video apparently released by the Islamic State group shows 25 men being shot dead in the ancient city of Palmyra, in Syria.
